Conventional image forming apparatuses fix a toner image on printing paper by means of a structure that sandwiches, between a pair of heated rollers, printing paper carrying an unfused toner image formed thereon. An image forming apparatus capable of such thermal fixing develops a temperature difference between a heating roller that contacts the surface on which the unfused toner image is formed and a pressure roller that contacts the surface on which no unfused toner image is formed, in order to achieve smooth and easy detachment of the printing paper from the pair of rollers. Specifically, there is provided a fan to cool down the pressure roller (see, for example, Patent Documents 1 to 3).
The pair of rollers are heated in the image forming apparatus when the printing paper is fixed. Since temperature falls upon coming in contact with the printing paper, however, the pair of rollers, being wider than the printing paper, develops a temperature difference between some parts thereof that contact the printing paper and the others that do not. This leads to local overheating, which in turn could cause undesirable wearing and damage of the end portions of the rollers. To eliminate this unevenness of temperature in the pressure roller's axial direction, a structure is being considered in which there is provided a ventilation path extending in the pressure roller's axial direction to cool down the entire pressure roller in a uniform manner (see, for example, Patent Document 4).
Some image forming apparatuses have an open/close cover to allow easy access to their interior in removing printing paper that could be jammed during transport and in carrying out maintenance. The structure facilitates removal of jammed paper by distancing the rollers sandwiching the printing paper when the open/close cover is opened.